Introduction: Unemployment is a significant problem for people with multiple sclerosis (MS). The MS Work Difficulties Questionnaire (MSWDQ-23) is a self-report tool to assess work-related problems in people with MS across three domains: physical, psychological/cognitive, and external barriers. The aim of this study was to assess the psychometric properties of the Spanish version of the MSWDQ-23.

Methods: A multicentre, non-interventional, cross-sectional study in adult patients with relapsing-remitting multiple sclerosis (RRMS) or primary progressive (PPMS) multiple sclerosis (McDonald 2010 criteria) was conducted. Socio-demographic and clinical characteristics as well as health-related quality of life using the 29- item Multiple Sclerosis Impact Scale (MSIS-29) were collected.

Results: A total of 201 subjects were studied (mean age: 43.9 years, 60% female, 86% with RRMS). Median Expanded Disability Status Scale (EDSS) (score: 2.0 [IQR: 1.0–3.5]). The employment rate was 47.3% (n = 95). The MSWDQ-23 was feasible (90% response rate), with high internal consistency and test-retest reliability (Cronbach's alpha = 0.94 and intraclass correlation coefficient-ICC > 0.87). MSWDQ-23 scores significantly and positively correlated with EDSS and both MSIS-29 physical and psychological subscales scores, showing an adequate convergent validity. Regarding construct validity, scores of patients with PPMS were higher than those of patients with RRMS, reaching statistically significance in MSWDQ-23 physical barriers domain and total scores.

Conclusion: The Spanish version of the MSWDQ-23 shows appropriate feasibility, reliability, and discriminative performance as a patient-reported outcome. MSWDQ-23 may be a valuable addition to measure the impact of a comprehensive spectrum of difficulties experienced by people with MS in the workplace.